1. Field of the Invention
The present invention relates generally to circuitry, and more specifically to circuitry that includes a charge pump.
2. Background
Charge pumps are used in any of a variety of systems, such as wireless and wire line communication systems, to provide a charge based on a phase error signal. The phase error signal indicates the difference between the phase of a first signal and the phase of a second signal. A greater phase difference generally produces a greater charge at the output of the charge pump. A lesser phase difference generally produces a lesser output charge.
The relationship between the output charge of a conventional charge pump and a phase difference indicated by the corresponding phase error signal is non-linear. This non-linear relationship or other non-linearities in a system can negatively impact the performance of the charge pump and/or the system. For example, the non-linear relationship may create a spur, which is unwanted energy at a frequency other than a targeted frequency. In another example, the non-linear relationship may increase the amplitude of the noise floor associated with the charge pump and/or the system.
What is needed is a linearized charge pump and system that addresses one or more of the aforementioned shortcomings of conventional charge pumps and systems.
In the drawings, like reference numbers indicate identical or functionally similar elements. Additionally, the leftmost digit(s) of a reference number identifies the drawing in which the reference number first appears.